A number of possible scenarios may then be invoked. Accretion of helium from a
companion on the surface of a sub-M\(_{\textrm {Ch}}\)  mass white dwarf can cause the surface
of the white dwarf to ignite [1]}. If the ensuing shock wave can
propagate and focus at the centre of the star, the white dwarf can explode via a
central detonation [2]}. Given the requirement of central ignition,
this scenario is not likely to lead to two distinct blobs of unburned material.
